Production of organic-inorganic semiconductor hybrid photodiodes

In this study, coumarin weight ratios of Coumarin: ZnO, Coumarin: CdO and Coumarin:TiO2 thin films synthesized by sol-gel method were formed by drop casting technique on p-Si. Morphological analysis of films produced at different coumarin weight ratios was performed with Scanning Electron Microscopy (SEM). Structural and optical analysis of synthesized ZnO, CdO and TiO2 powders were checked by X-ray diffractometer (XRD) and UV-Visible, respectively. ZnO, CdO and TiO2 nano powders were highly crystallized at high density and the forbidden energy ranges were 3.070, 2.31 and 3.219 eV, respectively. In addition, the effect of coumarin addition on the electrical properties of the Al/Coumarin:ZnO/p-Si/Al, Al/Coumarin:CdO/p-Si/Al and Al/Coumarin:TiO2/p-Si/Al photodiodes produced was investigated. The photodiode properties of organic-inorganic hybrid samples produced at different coumarin weight ratios were studied with Current-Voltage (I-V) characteristics under light intensities ranging from 20 to 100 mW/cm2. It was emphasized that all photodiodes produced had excellent rectifier properties with calculated rectification ratios. In addition, it was observed that the photocurrent of all photodiodes produced was smaller in dark conditions than under illumunated conditions. m values obtained from LogIph-LogP lines for different coumarin doping ratios showed that all diodes exhibited photoconductivity behavior. In addition, the transient Photocurrent-Time characteristics of the devices showed that the photodiodes produced were light-sensitive. The electrical behavior of the devices was investigated at different frequencies with Capacity-Voltage (C-V) and Conductivity-Voltage (G-V) measurements As the frequency increases, the capacity decreases and the conductivity increases. This was explained by the presence of the interface states of the samples produced. It was found that the series resistance (RS) and interface state density (Dit) values of the devices were significantly dependent on frequency and coumarin concentration. The obtained structural and electrical characterization results confirmed that all the devices produced can be used as optical sensors or photodiodes in optoelectronic applications.